1. Field of the Invention
The present invention relates generally to chip antennas and, more particularly, to chip antennas used in mobile communication apparatus for mobile communications and local area networks (LAN).
2. Description of the Related Art
It is demanded that antennas used for mobile communications and local area networks be small, and one type of antenna to satisfy this demand is a helical antenna.
The structure of a known type of helical antenna is shown in FIG. 5. A helical antenna generally indicated by 50 is constructed in the following manner. A linear conductor 51 is wound with a generally circular winding cross section 52 orthogonal to the winding axis C. One end of the conductor 52 is used as a feeding end 53, while the other end serves as a free end 54.
In the above-described helical antenna, evaluation and inspection of the conductor are performed by evaluating the antenna characteristics (resonant frequency, bandwidth, and so on) of the helical antenna. The antenna characteristics, however, vary depending on the state of grounding due to the structure of the antenna. Thus, the antenna characteristics of the helical antenna measured with a gaging instrument may differ from those of the antenna applied to practical use. It is, therefore, difficult to correctly evaluate and inspect a conductor used in a helical antenna.